Implantation assembly for a prosthetic ligament

ABSTRACT

An implantation assembly (16) has a guide element (22) for a ligament (18); a pulling element (24) comprising a pulling loop (26); and a manipulating loop (28). The guide element has a pulling aperture (36) towards a leading end (32), a manipulating aperture (38) towards a trailing end (34), and a connecting arrangement (40) for the ligament. The pulling and manipulating loops pass through the respective apertures. When the guide element emerges from a bone tunnel mouth, the manipulating loop is used to manipulate the guide element to a position where it overlies the tunnel mouth. The manipulating loop is secured to the pulling element and arranged such that a tensile load can be applied to the pulling element without generating a tensile load in the manipulating loop which could otherwise cause the guide element to be manipulated towards the anchoring position during passage along the bone tunnels.

This invention is concerned generally with the implantation of aprosthetic ligament, and in particular with providing an improvedimplantation assembly for use in guiding a prosthetic ligament to arequired position within a bone joint, and for anchoring one end of theligament. The invention is also concerned with a corresponding method ofimplanting a prosthetic ligament at a required position in a bone joint.

In the implantation of a prosthetic ligament in a bone joint e.g. theknee joint between tibial and femoral components (bones), it is usual todrill tunnels through the bones, and to pull the prosthetic ligamentthrough the tunnels until a required position is reached within thejoint. The ligament is then anchored against linear movement in eitherdirection. The anchoring may involve use of bone staples or otherintrusive fixations, which attach tensile elements (connected to eachend of the ligament) to suitable bone sites adjacent to the mouths ofthe bone tunnels.

Prosthetic ligaments can be made of synthetic material, provided that itis of a suitable implantable nature, and which may be woven.Alternatively, autogenous tissue harvested from the patient can be used,or allogenic tissue harvested from a suitable donor.

Prior endoscopic techniques developed for anterior cruciate ligament(ACL) reconstruction involved the use of a guide element which servedboth to guide the implantation of the ligament, and to secure one end ofthe ligament against axial movement in one direction. The guide elementis of such a construction that it does not need to be anchored inposition by physical intrusion into the bone.

The guide element used in these techniques provided easy guidance of theligament, by forming the lead element of a trailing implantation system.The guide element passes through the drilled-out bone tunnels and, uponexiting an upper mouth of one of the tunnels (e.g. when it projectsupwardly out of the femoral component), a simple manipulation of thedevice causes it to overlie the mouth of the tunnel. The guide elementthus provided tensile restraint for the ligament attached to the guideelement.

Guide elements of this type are known in the orthopaedic fraternity as‘Endobuttons™’. The guide element, or Endobutton™, is capable of beingmanipulated between a pulling position, in which it has a reducedlateral extent relative to the pulling direction, to an anchoringposition, in which it has a maximum lateral extent relative to thepulling direction (for overlying the mouth of the bone tunnel).

The trailing assembly which followed pulling-through of the guideelement typically comprised (a) further surgical cords (sutures) whichwere taken through a central pair of holes in the guide element, andthen connected together to complete the formation of a loop by knottingtogether of the ends of the sutures, and (b) the prosthetic ligament(whether it was made of synthetic material or tissue, be this autogenousor allogenic) attached to, or suspended from, the looped sutures in anyconvenient manner.

The present inventor developed an improved attachment device including aguide element or Endobutton™ of this type in the 1990s, the devicedisclosed in International Patent Publication No. WO-98/12991A1. Themain improvement on the prior design was the replacement of the knottedsuture, from which the prosthetic ligament was suspended, with a captiveknotless loop (or a non-captive variant of the same). Variants on thedesign of the guide element, and the means of connecting the knotlessloops to it, were also disclosed.

The technique disclosed in WO-98/12991A1 involved the use of a pullingsuture attached to the guide element through a first aperture, and aseparate flipping suture attached to the guide element through a secondaperture, which was spaced along the guide element. The pulling suturewas used to pull the guide element through the bone tunnels as describedabove and, following emergence of the guide element from the tunnelmouth, the flipping suture was used to manipulate the guide element tooverlie the mouth.

While the use of the use of knotless captive loops and their variantsdisclosed in WO-98/12991A1 provided distinct advantages over the priortechniques, in particular a superior strength over that of the priorknotted sutures, it is recognised that care must be taken during the useof the pulling and flipping sutures in order to avoid problems duringimplantation.

In particular, care must be taken to avoid causing the flipping sutureto accidentally become tense, which can cause the guide element to jamslightly, particularly at the entrance of a bone tunnel. Such mightoccur, for example, if the surgeon accidentally pulled on the flippingsuture during pulling of the guide element through the tunnels, or ifthe flipping suture became entangled with the pulling suture in such away as to impart a flipping load on the guide element. Should the guideelement jam at the tunnel entrance, dragging the guide element throughthe tunnel would then require greater application of force to thepulling suture, with an associated risk of breakage. If this shouldoccur then it could bring about a delay in the surgery, whilst thepulling suture is replaced. If a replacement pulling suture was notavailable in the operating room, a surgeon might then need to useanother device to complete the surgery. If this is not available in thesurgical inventory, this could cause the surgery to be jeopardised orcancelled.

According to a first aspect of the invention, there is provided animplantation assembly for a prosthetic ligament, for guiding theligament to a required position in a bone tunnel formed in a jointbetween two adjacent bones, and for anchoring one end of the ligament,the assembly comprising:

-   -   a guide element for the ligament, the guide element being        manipulatable between a pulling position in which a longitudinal        axis of the guide element extends generally parallel to a        pulling direction and an anchoring position in which its        longitudinal axis extends transversely of the pulling direction;    -   a pulling element comprising a pulling loop for pulling the        guide element through the bone tunnels; and    -   a manipulating loop for manipulating the guide element to        overlie a mouth at an end of one of the bone tunnels;    -   in which:    -   in the pulling position, the guide element defines a leading end        and a trailing end, a pulling aperture being provided towards        the leading end, a manipulating aperture being provided towards        the trailing end, and a connecting arrangement by which the        ligament can be connected to the guide element being provided        between the leading and trailing ends;    -   the pulling loop passes through the pulling aperture so that the        pulling element can be used to pull the guide element and the        trailing ligament through the bone tunnels with the guide        element disposed in the pulling position;    -   the manipulating loop passes through the manipulating aperture        so that, when the guide element emerges from the mouth at the        end of the tunnel, the manipulating loop can be used to        manipulate the guide element to the anchoring position where the        guide element can overlie the tunnel mouth, to facilitate        anchoring of the end of the ligament;    -   the manipulating loop is secured to the pulling element so that        the manipulating loop can be pulled along the bone tunnels by        the pulling element; and    -   the manipulating loop is arranged such that a tensile load can        be applied to the pulling element to pull the guide element, the        trailing ligament and the manipulating loop through the bone        tunnels without generating a tensile load in the manipulating        loop which could otherwise cause the guide element to be        manipulated towards the anchoring position during passage along        the bone tunnels.

The invention addresses the potential difficulties with priorassemblies, because the pulling element and manipulating (or ‘flipping’)loop are configured in a way that removes the potential for the guideelement to move towards the anchoring position, and so become ‘snagged’in the bone tunnels, during transit towards the mouth of the tunnel. Thepulling element and manipulating loop are effectively configured so asto ensure that, during the implantation procedure, only the pullingelement experiences tension (the flipping element effectively remainingsubstantially slack) until the guide element has cleared the mouth orexit of the tunnel, for example at the cortical side of a bone.Typically, the manipulating loop will be arranged so that part of theloop remains within the bone tunnel(s) after the guide element hascleared the mouth or exit of the tunnel, at a cortical end. Themanipulating loop may then be dragged through the tunnel to fully exposethe loop, and subsequently used as in prior surgical practice, inconjunction with the pulling element, to orient the guide element acrossthe mouth of the tunnel (that is, to move the guide element to theanchoring position, where it is disposed substantially perpendicularlyto the pulling direction). The guide element can then rest against thebone of the tunnel mouth, thereby securing the assembly within the bone,as in prior practice.

The pulling element may comprise a leading end and a trailing end, andthe pulling loop may form the trailing end. The pulling element maycomprise an anchor point for the manipulating loop, by which the loop issecured to the pulling element. The pulling loop may form the leadingand trailing ends (and so effectively the pulling element may take theform of a loop).

The pulling loop may comprise a portion of the pulling element which hasbeen folded back on itself and attached to a remainder or main part ofthe pulling element at a location which is part way along a lengththereof. Said location may define the anchor point for the manipulatingloop. Said portion of the pulling element may be attached by knottingthe portion to the remainder of the pulling element.

The pulling element may comprise first and second anchor points spacedalong a length of the element, one of the anchor points disposed closerto the trailing end and the other disposed closer to the leading end,and the manipulating loop may be secured to the pulling element so as tobe movable along the pulling element between the first and second anchorpoints. The pulling element may comprise an anchoring loop positionedbetween, and which may be defined by, the first and second anchorpoints, and the manipulating loop may extend through the anchoring loopso as to be secured to the pulling element and movable within the loopbetween the first and second anchor points.

The manipulating loop may be freely slidably movable through theanchoring loop, and along the length of the pulling element between thefirst and second anchor points.

The manipulating loop may be freely slidably movable between the firstand second anchor points, and secured against movement (in a directionalong a length of the manipulating loop) through the anchoring loop. Themanipulating loop may comprise a mounting which is slidable on theanchoring loop between the first and second anchor points, the mountingrestricting movement of the manipulating loop through the anchoringloop. This may provide the advantage that movement of the manipulatingloop through the anchoring loop, and so translation of the manipulatingloop along its length through the anchoring loop, is restricted. Thismay be desirable, for example, where the manipulating loop is formed sothat it includes a knot, by restricting the possibility of the knotcoming into contact with the guide element or an anchor point. Themounting may be a knot.

The manipulating loop may be secured to the pulling element at theanchor point, so that sliding movement of the manipulating loop relativeto the anchor point is prevented. Where the anchor point is a knot, themanipulating loop may be captured (and so secured) by the knot.

The manipulating loop may have a length which is sufficiently greaterthan a length of the pulling loop so that, when the pulling loop and theguide element are in-line (and so with the guide element in the pullingposition), the manipulating loop remains slack.

The pulling loop may have a length, the manipulating loop may have alength, and the length of the manipulating loop may be greater than adistance which is the sum of the length of the pulling loop and aspacing between the pulling aperture and the manipulating aperture. Inthis way, when the tensile load is applied to the pulling element topull the guide element, trailing ligament and manipulating loop throughthe bone tunnels, the generation of a tensile load in the manipulatingloop is avoided (and so the manipulating loop will remain substantiallyslack). The length of the manipulating loop may be the maximum distancebetween the trailing end of the pulling element (defined by the loop)and the anchor point. The spacing between the pulling and manipulatingapertures may be that which is defined by a straight line extendingparallel to the longitudinal axis of the guide element between an edgeor surface of the pulling aperture which is closest to the leading endof the guide element, and a corresponding edge or surface of themanipulating aperture. It will be understood that the lengths of thepulling and manipulating loops should be taken when the loops are tenseand so defining their maximum longitudinal extents.

The pulling loop and/or the manipulating loop may be formed by securinga length of elongate multi-stranded filamentous yarn or a monofilamentto itself using a knot. Alternatively, the pulling loop and/ormanipulating loop may comprise a cohesive assembly of twisted filaments,and/or may be an endless loop, manufactured according to the teachingsof International Patent Publication No. WO-99/47079, the disclosure ofwhich is incorporated herein by way of reference.

The assembly may comprise a connecting loop for connecting the ligamentto the guide element, the connecting loop being connected to theconnecting arrangement of the guide element. The connecting arrangementmay comprise a pair of apertures disposed between the pulling andmanipulating apertures, the connecting loop passing through theconnecting apertures so as to trail behind the guide element when theguide element is in the pulling position. The pulling and manipulatingapertures may together form the connecting arrangement, the connectingloop passing through the apertures so as to trail behind the guideelement when the guide element is in the pulling position. Theconnecting loop may comprise a cohesive assembly of twisted filaments,and/or may be an endless loop, manufactured according the teachings ofInternational Patent Publication No. WO-99/47079, the disclosure ofwhich is incorporated herein by way of reference. Alternatively, theconnecting loop may be formed by securing a length of elongate cord ormonofilament to itself using a knot.

The connecting arrangement may be arranged to directly receive theligament. The connecting arrangement may comprise a generally centralwaist portion of the guide element, which is of a smaller width (takentransverse to the longitudinal axis of the element) relative to adjacentportions of the guide element defining the leading and trailing ends.The waist portion may be adapted so that the ligament can pass aroundthe guide element in the area of the waist portion for connecting theligament to the guide element.

The connecting arrangement may comprise a pair of apertures disposedbetween the pulling and manipulating apertures. The pulling andmanipulating apertures may together form the connecting arrangement. Theconnecting apertures, or the pulling and manipulating apertures (asappropriate), may be adapted to receive fibres of the ligament forconnecting the ligament to the guide element. The ligament may be woven,and the apertures may be adapted to receive warp fibres of the ligamentin a region of the ligament which is free from wefts.

The guide element may be a metallic element and so of a metal or metalalloy, although other materials such as plastics or fibre reinforcedplastics composite materials may be employed. The guide element may begenerally elongate. The guide element may take the general form of anEndobutton™.

Reference is made herein to a manipulating loop, and to the pullingelement comprising a pulling loop. It will be understood that it ispreferable to provide such loops. However, other configurations notrequiring the use of such loops could be conceived, and are within thescope of the invention.

The assembly may comprise a prosthetic ligament. In the context of theinvention, the term ‘prosthetic’ encompasses replacement of a damagednatural ligament with a ligament which can be of synthetic material orbiological tissue (autogenous or allogenic).

According to a second aspect of the invention, there is provided amethod of implanting a prosthetic ligament at a required position in abone tunnel formed in a joint between two adjacent bones, and ofanchoring one end of the ligament, the method comprising the steps of:

-   -   connecting the prosthetic ligament to a connecting arrangement        of a guide element which is manipulatable between:        -   a pulling position in which a longitudinal axis of the guide            element extends generally parallel to a pulling direction;            and        -   an anchoring position in which its longitudinal axis extends            transversely of the pulling direction;    -   the guide element defining a leading end and a trailing end, a        pulling aperture being provided towards the leading end, a        manipulating aperture being provided towards the trailing end,        and the connecting arrangement being provided between the        leading and trailing ends;    -   coupling a pulling element comprising a pulling loop to the        guide element, the pulling loop passing through the pulling        aperture;    -   coupling a manipulating loop to the guide element, the        manipulating loop passing through the manipulating aperture;    -   securing the manipulating loop to the pulling element;    -   applying a tensile load to the pulling element to pull the guide        element, trailing ligament and manipulating loop through the        bone tunnels with the guide element disposed in the pulling        position;    -   arranging the manipulating loop such that the tensile load can        be applied to the pulling element without generating a tensile        load in the manipulating loop which could otherwise cause the        guide element to be manipulated towards the anchoring position        during passage along the bone tunnels; and    -   when the guide element emerges from a mouth at the end of the        tunnel, using the manipulating loop to manipulate the guide        element to the anchoring position where the guide element        overlies the tunnel mouth, to facilitate anchoring of the end of        the ligament.

Following manipulation of the guide element to the anchoring position,the pulling loop and manipulating loop may be released from the guideelement, optionally by severing the loops. Where the loops are formedusing a knot, the method may comprise severing the loops proximate tothe knots, suitably at a location immediately adjacent to the knots. Thesevered loops can then be removed by pulling on the knots, to draw thesevered loops through the respective apertures of the guide elements,thereby releasing them from the guide element.

Further features of the method of the second aspect of the invention maybe derived from the text set out above relating to the assembly of thefirst aspect of the invention.

According to a third aspect of the invention, there is provided animplantation assembly for a prosthetic ligament, for guiding theligament to a required position in a bone tunnel formed in a jointbetween two adjacent bones, and for anchoring one end of the ligament,the assembly comprising:

-   -   a guide element for the ligament, the guide element being        manipulatable between a pulling position in which a longitudinal        axis of the guide element extends generally parallel to a        pulling direction and an anchoring position in which its        longitudinal axis extends transversely of the pulling direction;    -   a pulling element comprising a pulling loop for pulling the        guide element through the bone tunnels; and    -   a manipulating loop for manipulating the guide element to        overlie a mouth at an end of one of the bone tunnels;    -   in which:    -   in the pulling position, the guide element defines a leading end        and a trailing end, a pulling aperture being provided towards        the leading end, a manipulating aperture being provided towards        the trailing end, and a connecting arrangement by which the        ligament can be connected to the guide element being provided        between the leading and trailing ends;    -   the pulling loop extends through the pulling aperture so that        the pulling element can be used to pull the guide element and        the trailing ligament through the bone tunnels with the guide        element disposed in the pulling position;    -   the manipulating loop extends through the manipulating aperture        so that, when the guide element emerges from the mouth at the        end of the tunnel, the manipulating loop can be used to        manipulate the guide element to the anchoring position where the        guide element can overlie the tunnel mouth, to facilitate        anchoring of the end of the ligament;    -   the manipulating loop is secured to the pulling element and        arranged so that the pulling element can be used to apply a        tensile load to the leading end of the guide element to pull the        guide element, trailing ligament and manipulating loop through        the bone tunnels without causing the manipulating loop to impart        a force on the trailing end of the guide element which could        otherwise cause the guide element to be manipulated towards the        anchoring position during passage along the tunnels.

Further features of the assembly of the third aspect of the inventionmay be derived from the text set out above relating to the assembly ofthe first aspect of the invention.

Embodiments of the present invention will now be described, by way ofexample only, in which:

FIG. 1 is a schematic side view of a typical type of bone joint withwhich the invention may be used, and which comprises a knee joint whichcomprises a tibial component and a femoral component;

FIG. 2 a view of an implantation assembly for a prosthetic ligament inaccordance with an embodiment of the present invention, for guiding animplant to a required position in the bone joint of FIG. 1;

FIG. 3 is a front view of the knee joint of FIG. 1, showing theimplantation assembly of FIG. 2 following location at the requiredposition;

FIG. 4 is an enlarged perspective view of a guide element forming partof the implantation assembly of FIG. 2;

FIG. 5 is a schematic view of the implantation assembly of FIG. 2,showing the guide element of FIG. 4 in a pulling position;

FIGS. 6 and 7 (on same sheet as FIG. 2) are enlarged views of parts ofthe implantation assembly shown in FIG. 2;

FIG. 8 a view of an implantation assembly for a prosthetic ligament inaccordance with another embodiment of the present invention, for guidingan implant to a required position in the bone joint of FIG. 1; and

FIG. 9 a view of an implantation assembly for a prosthetic ligament inaccordance with a further embodiment of the present invention, forguiding an implant to a required position in the bone joint of FIG. 1.

Referring first to FIG. 1 of the drawings, there is shown a schematicside view of a typical type of bone joint with which the invention maybe used, and which comprises a knee joint 10 which comprises a tibialcomponent 11 and a femoral component 12. Enlarged bone tunnels 13 and 14are drilled through the components 11 and 12, and in which a prostheticligament is to be implanted, but it will be noted that the bone tunnel14 merges into a passage 15 of smaller diameter, the purpose of whichwill be explained in more detail below.

The described embodiments of the invention provide implantationassemblies for a prosthetic ligament, which serve to guide the ligamentto a required position in a bone tunnel formed in a bone joint betweentwo adjacent bones, and also serves to anchor a leading end of theligament.

Accordingly, and turning now to FIG. 2, there is shown an implantationassembly for a prosthetic ligament, the assembly indicated generally byreference numeral 16, and the ligament by reference numeral 18. In theillustrated embodiment, the prosthetic ligament 18 is a woven syntheticmaterial ligament, but may comprise autogenous or allogenic biologicaltissue. The implantation assembly 16 can be used to guide the ligament18 to a required position in the bone tunnel formed in a bone jointbetween two adjacent bones, in this case in the bone tunnels 13 and 14in the knee joint 10 shown in FIG. 1. The implantation assembly 16 alsoserves to anchor a leading end 20 of the ligament 18.

The implantation assembly 16 generally comprises a guide element 22 forthe ligament 18, a pulling element 24 comprising a pulling loop 26 forpulling the guide element 22 through the bone tunnels 13 and 14, and amanipulating loop 28. The manipulating loop 28 is for manipulating theguide element 22 to overlie a mouth 23 at an end of the bone tunnel 14,as shown in the schematic front view of FIG. 3, showing the assembly 16located at the required position.

The guide element 22 is a generally elongate element, and is typicallymetallic, of a suitable metal or metal alloy material. In particular,the guide element 22 can take the form of a metal bar, and may take theform of an Endobutton™, such as that which is commercially availablefrom Smith & Nephew in the UK. The guide element 22 is shown separatelyin the enlarged perspective view of FIG. 4, and is manipulatable betweena pulling position, which is shown in the highly schematic view of FIG.5, and an anchoring position, which is shown in FIG. 3. In the pullingposition, a longitudinal axis 30 of the guide element 22 extendsgenerally parallel to a pulling direction through the bone tunnels 13and 14, whilst in the anchoring position, the longitudinal axis 30extends transversely of the pulling direction, and is typically orientedperpendicular to the pulling direction (this depending upon featuresincluding the angle of the bone tunnel 14 relative to the general planeof the bone surface 33, and bone surface features).

When a tensile load is applied to the pulling element 24, the guideelement 22 orientates itself so that its longitudinal axis 30 extendsgenerally parallel to the axes of the tunnels 13 and 14 and in thepulling direction, so that it presents minimum lateral projection fromthis axis. The metal bar forming the guide element 22 typically has alength of around 12 mm, a width of around 4 mm, and a thickness ofaround 1.5 mm. The final passage 15 in the femoral component 12 istherefore formed so that it is slightly larger in diameter than thetransverse dimension of the guide element 22, thereby allowing thepulling element 24 to pull the guide element 22 through bone tunnel 14and narrow passage 15, and then emerging from the mouth 23. FIG. 3 showsthe guide element 22 after it has been manipulated to a transverselyextending position in which it overlies the mouth 23, and therebyprovides anchorage for the leading end 20 of the ligament 18.

In the pulling position of the guide element 22 (in FIG. 2), it definesa leading end 32 and a trailing end 34, a pulling aperture 36 beingprovided towards the leading end 32, a manipulating aperture 38 beingprovided towards the trailing end 34, and a connecting arrangement 40being provided between the leading and trailing ends 32 and 34. Theconnecting arrangement 40 serves for connecting the ligament 18 to theguide element 22 and, in the illustrated embodiment, comprises a pair ofconnecting apertures 42, the purpose of which will be described below.In a variation on the illustrated embodiment (not shown), the pullingand manipulating apertures 36 and 38 may define the connectingarrangement 40, in which case the apertures will typically be of largerdimension and which may be elongated in a length direction of the guideelement 22.

As shown in FIG. 2, and the enlarged view of FIG. 6, the pulling loop 26of the pulling element 24 passes through the pulling aperture 36, sothat the pulling element 24 can be used to pull the guide element 22 andtrailing ligament 18 through the bone tunnels 13 and 14 with the guideelement disposed in the pulling position. The manipulating loop 28passes through the manipulating aperture 38 so that, when the guideelement 22 emerges from the mouth 23 at the end of the tunnel 14, themanipulating loop can be used to manipulate the guide element 22 to theanchoring position (FIG. 3), where the guide element can overlie thetunnel mouth. This facilitates subsequent anchoring of the end 20 of theligament 18, by contact between the surface 33 of the femoral component12 and the guide element 22.

As also shown in FIG. 2, and the enlarged view of FIG. 7, themanipulating loop 28 is secured to the pulling element 24 so that themanipulating loop can be pulled along the bone tunnels 13 and 14 by thepulling element. The manipulating element 28 is also arranged such thata tensile load can be applied to the pulling element 24 to pull theguide element 22, trailing ligament 18 and manipulating loop 28 throughthe bone tunnels 13 and 14 without generating a tensile load in themanipulating loop 28 which could otherwise cause the guide element to bemanipulated towards the anchoring position during passage along the bonetunnels. The invention thereby addresses the potential difficulties withprior assemblies, by preventing inadvertent flipping of the guideelement 22.

The implantation assembly 16, and its method of use to implant theligament 18, will now be described in more detail.

The pulling element 24 is a multi-stranded filamentous yarn, which maybe wound or braided, but could be a monofilament. The pulling element 24is typically formed of a suitable implantable material, or of a materialwhich is suitable for coming into contact with body tissue. The pullingelement 24 comprises a leading end 44 and a trailing end 46, which isdefined by the pulling loop 26. The pulling element 24 also comprises ananchor point 48, which is formed by folding the cord forming the pullingelement 24 back on itself, to form the pulling loop 26, and thenknotting the cord to a remainder or main part 50 of the pulling element.In the embodiment of FIG. 2, the knot which defines the anchor point 48forms a first anchor point, and a second anchor point 52 is formed,spaced along a length of the pulling element 24 from the first anchorpoint. The second anchor point again takes the form of a knot. In thisway, an anchoring loop 54 is formed between the first and second knots48 and 52. The manipulating loop 28 extends through the anchoring loop54, and is thereby secured to the pulling element 24 in such a way thatthe manipulating loop is moveable within the anchoring loop between thefirst and second knots 48 and 52.

In use, when the implantation assembly 16 is dragged through the bonetunnels 13 and 14, (in FIG. 1) the manipulating loop 28 will slide alongthe anchoring loop 54 until it comes into contact with the knot formingthe first anchor point 48. In this way, the manipulating loop 28 will bedragged along the tunnels 13 and 14 by the pulling element 24.

The manipulating loop 28 is also typically of a multi-strandedfilamentous yarn of implantable material (or material suitable forcoming into contact with body tissue), but again may be a monofilament.The manipulating loop 28 is formed by threading the cord through theanchoring loop 54, manipulating aperture 38 on guide element 22 and thenknotting its two ends 56 and 58 together to form a knot 60.

As can be appreciated from FIGS. 2 and 3, part of the manipulating loop28 may remain within the bone tunnel 14, in particular the smallerdiameter passage 15, following emergence of the guide element 22 fromthe tunnel mouth 23. A surgeon would therefore draw the remainingportion of the manipulating loop 28 up out of the passage 15, and theloop can then be tensioned to a sufficient degree to manipulate theguide element 22 to the anchoring position. A tensile force can then beexerted on the ligament 18 extending back down through the tunnel 13 inthe tibial component 11, so that the guide element 22 sits on the bonesurface 33, anchoring the end 20 of the ligament 18.

Following manipulation of the guide element 22 to the anchoringposition, the pulling loop 26 and manipulating loop 28 are released fromthe guide element 22, by severing the loops. The loops 26 and 28 aresevered proximate to the respective knots 48 and 60, suitably at alocation immediately adjacent to the knots. The severed loops 26 and 28can then be removed by pulling on the knots 48 and 60, to draw thesevered loops through the respective apertures 36 and 38 of the guideelement 22, thereby releasing the loops from the guide element.

The ligament 18 is connected to and so suspended from the guide element22 by means of a connecting loop 62, which is typically a cohesiveassembly of twisted filaments in the form of an endless loop,manufactured according to the teachings of WO-99/47079. The connectingloop 62 passes through the connecting apertures 42 in the guide element22, and the ligament 18 is threaded through the loop 62. In this way,when the guide element 22 is drawn through the bone tunnels 13 and 14,the ligament 18 trails the guide element and so is drawn through thebone tunnels. Reference is made herein to the guide element taking up apulling position, in which the longitudinal axis 30 of the guide elementextends generally parallel to the pulling direction. One factoraffecting the ability of the guide element 22 to adopt a position whichis precisely parallel to the pulling direction is the relative thicknessof the connecting loop 62. In practice, the thickness of the connectingloop 62 may be such that the guide element 22 lies at an angle which isslightly displaced from (and so slightly non-parallel to) the pullingdirection.

The arrangement whereby a tensile load can be applied to the pullingelement 24 without generating a tensile load in the manipulating loop 28is as follows. As shown in FIG. 5, the pulling loop 26 of the pullingelement 24 is of a length L₁ (when tense) between the trailing end 46 ofthe pulling element 24 and a leading side of the knot 48. Themanipulating loop 28 is slack when the assembly 16 is in the position ofFIG. 5, during passage along the bone tunnels 13 and 14. Themanipulating loop 28 has a length which is greater than a distance L₂,which is the sum of the length L₁ of the pulling loop 26 and a spacingL₃ between the pulling and manipulating apertures 36 and 38 (taken in adirection along the longitudinal axis between edges of the apertureswhich are closest to the leading end 32). This ensures that tensioningof the pulling element 24 cannot result in a tensile load in themanipulating loop 28 which could otherwise cause the guide element 22 tobe moved towards its anchoring position, with the possibility of thenbecoming jammed in one of the bone tunnels 13 or 14, and in particularat an entrance to the smaller diameter passage 15.

Turning now to FIG. 8, there is shown an implantation assembly inaccordance with another embodiment of the present invention, theassembly indicated generally by reference numeral 16 a. Like componentsof the assembly 16 a with the assembly 16 of FIGS. 2 to 7 share the samereference numerals, with the addition of the suffix “a”. Only thesubstantial differences between the assemblies 16 a and 16 will bedescribed herein in detail.

The assembly 16 a is of like construction to the assembly 16, save thata manipulating loop 28 a is freely slidably moveable between first andsecond anchor points in the form of knots 48 a and 52 a, but includes amounting 64 which restricts movement of the manipulating loop 28 athrough an anchoring loop 54 a. The mounting 64 takes the form of a knotformed in the manipulating loop 28 a, which typically takes the form ofa slip-knot. The knot 64 includes a mounting loop 66 which can slidealong a branch 68 of the anchoring loop 54 a between the knots 48 a and52 a.

This provides the advantage that, whilst the manipulating loop 28 a canslide between the knots 48 a and 52 a, the cord forming the manipulatingloop 28 a cannot pass through the anchoring loop 54 a. This prevents theknot formed in the anchoring loop 28 a (not shown—60 in FIG. 2) fromcoming into contact with the guide element 22, and in particular frombecoming located at a position where it would reside between the bonesurface 33 and the guide element 22. This also prevents the knot in theanchoring loop 28 a from interfering with the anchoring loop 54 a, whichcould hamper movement of the manipulating loop 28 a along the pullingelement 24 a and so manipulation of the guide element 22 to theanchoring position.

Turning now to FIG. 9, there is shown an implantation assembly inaccordance with another embodiment of the present invention, theassembly indicated generally by reference numeral 16 b. Like componentsof the assembly 16 b with the assembly 16 of FIGS. 2 to 7 share the samereference numerals, with the addition of the suffix “b”. Again, only thesubstantial differences between the assemblies 16 b and 16 will bedescribed.

In this embodiment, a pulling element 24 b includes only a single anchorpoint in the form of a knot 48 b. A manipulating loop 28 b is secured tothe pulling element 24 b at the anchor point 48 b, and intertwined withthe pulling element cord during formation of the knot, so that the loop28 b is captured by the knot 48 b. In this way, sliding movement of themanipulating loop 28 b relative to the knot 48 b is prevented. In otherwords, the manipulating loop 28 b cannot move along a length of thepulling element 24 b. This again offers advantages in terms ofpreventing a knot (not shown) in the manipulating loop 28 b from cominginto contact with a guide element (also not shown—22 in FIG. 2), andalso avoids the requirement to provide a second anchoring point, such asthe anchor point 52, or to form an anchoring loop such as the loop 54,shown in FIG. 2.

Various modifications may be made to the foregoing without departingfrom the spirit or scope of the present invention.

The pulling loop may form the leading and trailing ends, and soeffectively the pulling element may take the form of a loop.

The pulling loop and/or manipulating loop may comprise a cohesiveassembly of twisted filaments, and/or may be an endless loop,manufactured according to the teachings of WO-99/47079.

The pulling and manipulating apertures may together form the connectingarrangement, the connecting loop passing through the apertures so as totrail behind the guide element when the guide element is in the pullingposition.

The connecting apertures, or the pulling and manipulating apertures (asappropriate), may be adapted to receive fibres of the ligament forconnecting the ligament to the guide element. The ligament may be woven,and the apertures may be adapted to receive warp fibres of the ligamentin a region of the ligament which is free from wefts.

The connecting loop may be formed by securing a length of elongate cordor monofilament to itself using a knot.

The connecting arrangement may be arranged to directly receive theligament. The connecting arrangement may comprise a generally centralwaist portion of the guide element, which is of a smaller width (takentransverse to the longitudinal axis of the element) relative to adjacentportions of the guide element defining the leading and trailing ends.The waist portion may be adapted so that the ligament can pass aroundthe guide element in the area of the waist portion for connecting theligament to the guide element.

Reference is made herein to a manipulating loop, and to the pullingelement comprising a pulling loop. Other configurations not requiringthe use of such loops could be conceived, and are within the scope ofthe invention.

The invention claimed is:
 1. An implantation assembly for a prostheticligament, for guiding the ligament to a required position in bonetunnels formed in a joint between two adjacent bones, and for anchoringone end of the ligament, the assembly comprising: a guide element forthe ligament, the guide element being manipulatable between a pullingposition in which a longitudinal axis of the guide element extendsparallel or generally parallel to a pulling direction and an anchoringposition in which its longitudinal axis extends transversely of thepulling direction; a pulling element comprising a pulling loop forpulling the guide element through the bone tunnels; and a manipulatingloop for manipulating the guide element to overlie a mouth at an end ofone of the bone tunnels; in which: in the pulling position, the guideelement defines a leading end and a trailing end, a pulling aperturebeing provided towards the leading end, a manipulating aperture beingprovided towards the trailing end, and a connecting arrangement by whichthe ligament can be connected to the guide element being providedbetween the leading and trailing ends; the pulling loop passes throughthe pulling aperture so that the pulling element can be used to pull theguide element and the trailing ligament through the bone tunnels withthe guide element disposed in the pulling position; the manipulatingloop passes through the manipulating aperture so that, when the guideelement emerges from the mouth at the end of one of the bone tunnels,the manipulating loop can be used to manipulate the guide element to theanchoring position where the guide element can overlie the mouth at theend of one of the bone tunnels, to facilitate anchoring of the end ofthe ligament; the manipulating loop is secured to the pulling element sothat the manipulating loop can be pulled along the bone tunnels by thepulling element; and the manipulating loop is arranged such that atensile load can be applied to the pulling element to pull the guideelement, the trailing ligament and the manipulating loop through thebone tunnels without generating a tensile load in the manipulating loopwhich could otherwise cause the guide element to be manipulated towardsthe anchoring position during passage along the bone tunnels.
 2. Anassembly as claimed in claim 1, in which the pulling element comprises aleading end and a trailing end, the pulling loop forming the trailingend of the pulling element, and in which the pulling element comprisesan anchor point for the manipulating loop, by which the manipulatingloop is secured to the pulling element.
 3. An assembly as claimed inclaim 2, in which the pulling loop comprises a portion of the pullingelement which has been folded back on itself and attached to a main partof the pulling element at a location which is part way along a length ofthe pulling element, said location defining the anchor point for themanipulating loop.
 4. An assembly as claimed in claim 2, in which thepulling element comprises first and second anchor points spaced along alength of the pulling element, one of the anchor points disposed closerto the trailing end of the pulling element and the other disposed closerto the leading end of the pulling element, and in which the manipulatingloop is secured to the pulling element so as to be movable along thepulling element between the first and second anchor points.
 5. Anassembly as claimed in claim 4, in which the pulling element comprisesan anchoring loop positioned between and defined by the first and secondanchor points, and in which the manipulating loop extends through theanchoring loop so as to be secured to the pulling element and is movablewithin the anchoring loop between the first and second anchor points. 6.An assembly as claimed in claim 5, in which the manipulating loop isfreely slidably movable through the anchoring loop, and along the lengthof the pulling element between the first and second anchor points.
 7. Anassembly as claimed in claim 5, in which the manipulating loop is freelyslidably movable between the first and second anchor points, and securedagainst movement through the anchoring loop.
 8. An assembly as claimedin claim 7, in which the manipulating loop comprises a mounting which isslidable on the anchoring loop between the first and second anchorpoints, the mounting restricting movement of the manipulating loopthrough the anchoring loop.
 9. An assembly as claimed in claim 8, inwhich the mounting is a slip-knot.
 10. An assembly as claimed in claim2, in which the manipulating loop is secured to the pulling element atthe anchor point, so that sliding movement of the manipulating looprelative to the anchor point is prevented.
 11. An assembly as claimed inclaim 10, in which the anchor point is a knot, and in which themanipulating loop is captured by the knot.
 12. An assembly as claimed inclaim 1, in which the pulling loop forms leading and trailing ends ofthe pulling element.
 13. An assembly as claimed in claim 1, in which themanipulating loop has a length which is greater than a length of thepulling loop so that, when the pulling loop and the guide element arein-line, the manipulating loop remains slack.
 14. An assembly as claimedin claim 1, in which the pulling loop has a length, the manipulatingloop has a length, and in which the length of the manipulating loop isgreater than a distance which is a sum of the length of the pulling loopand a spacing between the pulling aperture and the manipulatingaperture.
 15. An assembly as claimed in claim 14, in which the length ofthe manipulating loop is a maximum distance between the trailing end ofthe pulling element and the anchor point; and the spacing between thepulling and manipulating apertures is that which is defined by astraight line extending parallel to the longitudinal axis of the guideelement between an edge of the pulling aperture which is closest to theleading end of the guide element, and a corresponding edge or surface ofthe manipulating aperture.
 16. An assembly as claimed in claim 1,comprising a connecting loop for connecting the ligament to the guideelement, the connecting loop being connected to the connectingarrangement of the guide element.
 17. A method of implanting aprosthetic ligament at a required position in bone tunnels formed in ajoint between two adjacent bones, and of anchoring one end of theligament, the method comprising the steps of: connecting the prostheticligament to a connecting arrangement of a guide element which ismanipulatable between: a pulling position in which a longitudinal axisof the guide element extends parallel or generally parallel to a pullingdirection; and an anchoring position in which its longitudinal axisextends transversely of the pulling direction; the guide elementdefining a leading end and a trailing end, a pulling aperture beingprovided towards the leading end, a manipulating aperture being providedtowards the trailing end, and the connecting arrangement being providedbetween the leading and trailing ends; coupling a pulling elementcomprising a pulling loop to the guide element, the pulling loop passingthrough the pulling aperture; coupling a manipulating loop to the guideelement, the manipulating loop passing through the manipulatingaperture; securing the manipulating loop to the pulling element;applying a tensile load to the pulling element to pull the guideelement, trailing ligament and manipulating loop through the bonetunnels with the guide element disposed in the pulling position;arranging the manipulating loop such that the tensile load can beapplied to the pulling element without generating a tensile load in themanipulating loop which could otherwise cause the guide element to bemanipulated towards the anchoring position during passage along the bonetunnels; and when the guide element emerges from a mouth at an end ofone of the bone tunnels, using the manipulating loop to manipulate theguide element to the anchoring position where the guide element overliesthe mouth at the end of one of the bone tunnels, to facilitate anchoringof the end of the ligament.
 18. A method as claimed in claim 17, inwhich the pulling loop and manipulating loop are each formed using aknot, and in which, following manipulation of the guide element to theanchoring position, the pulling loop and manipulating loop are releasedfrom the guide element by severing the pulling and manipulating loopsand then pulling on the knots to draw the severed pulling andmanipulating loops through the respective apertures of the guideelements.
 19. A method as claimed in claim 18, comprising severing thepulling and manipulating loops at a location immediately adjacent to theknots.
 20. An implantation assembly for a prosthetic ligament, forguiding the ligament to a required position in bone tunnels formed in ajoint between two adjacent bones, and for anchoring one end of theligament, the assembly comprising: a guide element for the ligament, theguide element being manipulatable between a pulling position in which alongitudinal axis of the guide element extends parallel or generallyparallel to a pulling direction and an anchoring position in which itslongitudinal axis extends transversely of the pulling direction; apulling element comprising a pulling loop for pulling the guide elementthrough the bone tunnels; and a manipulating loop for manipulating theguide element to overlie a mouth at an end of one of the bone tunnels;in which: in the pulling position, the guide element defines a leadingend and a trailing end, a pulling aperture being provided towards theleading end, a manipulating aperture being provided towards the trailingend, and a connecting arrangement by which the ligament can be connectedto the guide element being provided between the leading and trailingends; the pulling loop extends through the pulling aperture so that thepulling element can be used to pull the guide element and the trailingligament through the bone tunnels with the guide element disposed in thepulling position; the manipulating loop extends through the manipulatingaperture so that, when the guide element emerges from the mouth at theend of one of the bone tunnels, the manipulating loop can be used tomanipulate the guide element to the anchoring position where the guideelement can overlie the mouth at the end of one of the bone tunnels, tofacilitate anchoring of the end of the ligament; the manipulating loopis secured to the pulling element and arranged so that the pullingelement can be used to apply a tensile load to the leading end of theguide element to pull the guide element, trailing ligament andmanipulating loop through the bone tunnels without causing themanipulating loop to impart a force on the trailing end of the guideelement which could otherwise cause the guide element to be manipulatedtowards the anchoring position during passage along the bone tunnels.